Research on diversified retrieval of information has commonly focused on diversifying search results due to ambiguity in user intent, which is referred to as extrinsic diversity. Conventional search engines oftentimes provide support for extrinsic diversity in search results. Accordingly, the search engine can attempt to cover potentially diverse information retrieval intents of many users for a given query. For instance, the query “Cardinals” may trigger an extrinsically diverse algorithm that attempts to return search results concerning “Cardinals baseball,” “Cardinals football,” “Catholic Cardinals,” and the like. By supporting extrinsic diversity, conventional search engines attempt to supply search results related to information retrieval intents of different users for a common query.
Further, conventional research on web search has focused on optimizing and evaluating single query sessions. However, many user queries can be part of more complex tasks that span multiple queries across one or more search sessions. Thus, conventional approaches oftentimes lead to users issuing multiple queries to obtain documents on different aspects of a question or topic on which they desire to find more information or explore.